Adventure Falls
by suzukipot
Summary: When twins Mabel and Dipper Pines find a secret passageway in the old tree they meet two of Ooo's mightiest adventurers.
1. Chapter 1

"Come on Mabel look. This is where I found the book." Dipper hurrily wondered through the forrest with his sister following close behind. The book he'd found was clutched to his chest.

"Why are you even showing me," Mabel asked,the sleeves on her sweater drooping.

"Because it's important. What if there's something elsew I didn't see?" Dipper started to knock on tree trunks. One sounded hollow.

"This one!" Dipper opened the door. There was nothing but cobwebs.

"Well that was exciting," Mabel muttered.

"Wait a second...," Dipper bent down and looked at the floor. He put his hand down,layed it flat and felt around until he found...a handel. He pulled on it so that the floor stared to raise. A bottomless cavern awaited them.

Dipper backed up. "Woah. What do you thinks down there?"

Mabel leaned in."I don't know. Let's go see!" She tried to lean in more but Dipper grabbed the back of her sweater.

"Mabel we don't know what's down there. We need to do more research before we just- Mabel? Mabel!"

Mabel jumped in the pit. Dipper went in after her.

Dipper slowly woke up. "Huh? What?" He sat up and looked around.

"Mabel? Mabel where are you?"

"Dipper." A faint cry was heard.

"Mabel?"

"Dipper! Over here!"

Dipper ran to where he heard Mabel scream.

"Oh...my..." Dipper looked around his surroundings. Everything was dark. There were scattered parts to machienes,rocket ships, and other assorted things. And in the middle of it was a hamsterwheel.

And Mabel was running on it. "Dipper! A bunch on gnomes got me...again. And they're making me run on this hamsterwheel."

Short,green creatures with beards and hats turned towards Dipper.

"So you're the twin we've been hearing all about," one of them said. "You know, we had to listen to your sister here talk for hours. On and on about this and that. It was then we realized that we'd found the perfect powersource for our plan."

"Let go of my sister," Dipper threatened.

The gnome laughed. "Or what? You're outnumbered kid!" The other gnomes came out and surrounded Dipper.

"Mabel,run!"

Mabel jumped off the hamster wheel and ran towards Dipper. She swiped at the gnomes and got them away from Dipper.

"Come on!"

They ran towards the exit. Once they escaped they laid on the grass and tried to catch their breath.

"I think...we're safe."

Suddenly,a large black wolf jumped in front of them. They screamed.

"Oh...please please. Children let me explain. I am but a simple Whywolf."

"Why...wolf?"

"Yes," the Whywolf said,matter of factly.

Then,someone jumped and kicked the Whywolf in the face. It was a boy wearing black shorts,a blue shirt and carrying a sword. There was a dog following him. The Whywolf whimpered and ran away.

"Nice one Finn," The dog said,high fiving the boy.

Mabel gasped. "A talking dog."

Mabel and Dipper stood up. Finn and Jake looked at them.

"Woah," Finn said. "Are you two..."

Mabel ran over and started to pet Jake.

"Finn who are these guys," Jake asked,looking at Mabel.

" I don't know. I- I don't think they're fish people. They don't have gills."

"Fish people," Dipper said,getting confused. "Me and my sister are human."

"Really," Finn said, starting to smile. " That's bombastic!"

"Where are we? Who are you guys? And why do you care that we're humans?"

"Well I'm Finn and he's Jake. And you're in Ooo dude."

"Ooo," Mabel said,waving her hands in the air.

"Ooo," Dipper asked. "Hm... the secret passage in the ground must have brought us here! Maybe that's where the person who wrote this book went to."

"Wait...did you guys say you weren't from here?"

"No. We're from a place called Gravity Falls,Oregon. We fell through a cavern in the bottom of a tree and ended up...here!"

"Finn," Jake whispered. "I don't think these kids are right in the head."

"Oh come on Jake," Finn said. " They probably got abandoned by their paents. We should take them home."

"Well...if you say so."

Mabel was talking about a mile a minute. "Oh my gosh do you guys have zombies or flying dolphins or vampires?" Mabel tugged on Finn's shirt.

"Uh well...Marceline is a vampire. Do you guys want to meet her?"

"Yes,"Mabel said,throwing her arms in the air.

"Great let's go."

So the four set out to look for Marceline.


	2. Chapter 2

Author's Note: Some creative liscence went into this. Such as so and so making the book and stuff like that. Enjoy.

"Hey Marceline," Finn called out,when they got to Marceline's house.

Marceline looked around at them. "Hey Finn." She looked at Dipper and Mabel. "Who're the squirts?"

"Oh. Marceline this is..." he trailed off,realizing he hadn't caught their names.

"Dipper Pines. Detective for Gravity Falls," Dipper said,a little smug.

Mabel was speechless and just stared at Marceline. Marceline floated over towards the two and put her arms around them.

"Say...you two look like you like a little mystery. Mind solving one for me?"

Dipper nodded. "Whatever you need we'll solve."

"Good." Marceline floated towards the front door of her house. " My house is haunted by some spirits," she wiggled her fingers. "Go see what's going on."

"We're on it. Come on Mabel."

"We get to go in a vampire's house? Cool!"

Marceline giggled. "Have fun." She opened the door,let them in and locked it.

"Marceline what're you doing," Finn said hysterically. "They're just kids!"

"Don't worry Finn. I'm just pranking them. There's nothing in there but some cardboard cutouts." Marceline and Finn looked in the window.

"Ooooo what's this",Mabel said touching Marceline's axe bass.

"Mabel don't touch anything. We're just here to get rid of the spirits." Dipper redied his camera and looked around. He looked up the ladder.

"I wonder what's up here..." he put a hand and foot on the rails. Suddenly, one of the cardboard cutouts sprang up. Dipper screamed and Mabel lunged at the cutout. She landed on the couch with an 'umph'

"Ow," Mabel groaned,holding her head.

Dipper rushed over to her. "What the? Cardboard?" Outside he heared wild laughing. The door opened and the two walked out.

"Wow Marceline. That was a good prank," Finn laughed.

"Prank," Dipper said.

"Yeah," Marceline replied. "It's kinda my thing."

"But...I don't get it. Are you good or bad or..."

"Hey. Don't break a blood vessel kid. Hey Finn. Why don't you take the squirts to Bonnibel.I'm sure she'd like to see them," Marceline said,floating above Dipper and giving his head a nougie.

"Yeah sure. Come on guys."

They walked into the Candy Kingdom. Mabel's eyes went wide.

"There's...candy...everywhere," was the only words she could speak. Mabel started picking parts off candy hauses and the street. She licked and chewed it. They went in the Candy Castle.

"Hey PB," Finn greeted.

"Hello Finn."

"I...have some people you might want to meet." He stepped out of the way to show Mabel and Dipper.

"Oh my. Finn are they-"

"Yep."

"But..where did you find them?"

"What are we? Science expiraments? Why are we so special to you people," Dipper asked,clearly confused.

"Oh..poor things. Here et me explain. You see,long ago there was a a thing called the Great Mushroom War. It destroyed many inventions,businesses and...humans like yourselves.

For all we knew Finn was the last surviving human in all of Ooo but now you two have shown up. Where are you from?"

"We're from a place called Gravity Falls. We found some sort of...trap door that led us to this crazy,messed up world," Dipper almost yelled.

"Can I eat your hair," Mabel asked,reaching for Bubblegum's hair.

"A trap door ,hmm? It sounds like portal of some sorts. If youshow me where it is I might be able to get you two back to your world."

"Wait," Dipper said,holding up the book. "Do you know who made this book?"

Bubblegum gasped. "This looks like the book Jake's father made!"

"What," Finn and Jake said simultaniously. Jake grabbed the book.

"You know Finn...this does look kind of familiar."

"Really? I don't remember it."

"You were probably too young to remember it. Dad only had it out a couple of times to write."

"Wait. This belonged to your dad? Er,uh, both of you guy's dad? What was he like?"

"Well...he was real manly. He always wanted me and Finn to fight and he built a dungeon for us."

Dipper rubbed his chin. "Hmm...interesting."


	3. Chapter 3

"So all we need to do is talk to your dad."

"Well...our dad is kinda...dead."

"Darn it." Dipper started to think. "What about your mom? Is your mom still alive?"

"She's dead too."

"So you're telling me that me and my sister are stuck in this...place with no answers on how to get back. And I can't even figure out who wrote this book or why?" Dipper threw the book on the ground and panted.

"Calm down,calm down. I know a way to get you both back," Bubblegum said.

"Really?"

"Yes. I told you. We just need to create another portal. We could try to get you through the original one but I feel another one will be better. And,besides,once we close the second portal the first one will also close,because they are interconnected."

"Well...fine then."

"What? Dipper why would you want to leave? I could live here forever!" Mabel wiped sugar from her mouth.

" No Mabel. We have to go back home."

Mabel struggled to stand but when she did she panted a bit. " I don't want to go though."

" Mabel we have to," Dipper said sternly. " Grunkle Stan,wendy,and Soos will wonder where we've been. Unless there's,you know some kind of odd time continuim here." Dipper shrugged.

"No! I'm never leaving."

" You guys! Be quiet. I'm constructing the potion that will make the portal appear," Bubblegum said, standing over her science equipment.

"Well fine I guess we'll sit here and wait."

Suddenly, Dipper heard the front doors to the castle slam.

"Huh? Mabel?"

Dipper stood up and ran outside. He saw Mabel running towards a forest.

"Mabel? What're you doing?" Dipper ran after her.

Then Mabel just stood there. It looked like she was looking at something.

"M-Mabel?"

Then, Mabel was sucked into something,it looked like a giant mouth.

"Mabel! I'm coming!" Dipper grabbed onto Mabel's foot as they were sucked in.

They landed on a cloud. Dipper stood up.

"W-where are we?"

"How do you not know where you are," a low smug voice asked.

"Well...we're...out of towners."

"You're in Lumpy Space."

"And...you are?"

"Mah names Lumpy Space Princess. I'm visiting my parents cuz they've been like,worried about me and stuff."

"Ok so can we just," Dipper tried to step down and almost fell off the cloud.

"Yeah only Lumpy Space People can get around here. Smooth people like you guys need my help."

"Well... I guess so," Dipper said,not really wanting to cause a fight by arguing.

"Well I guess you're lucky that my parents let me use the car." LSP jumped in. "Well? Come on! Get in."

Dipper turned towards Mabel.

"Mabel I'm sorry but we can't stay."

Mabel sighed. "I know."

"Hey. Quit having a moment and get in my lumpin' car!"

Dipper and Mabel got in LSP's car. She drove to the exit.

"There. You can go now."

"Thanks," Dipper said getting out and standing on the ground.

"Whatever," LSP muttered.

"You're squishy," Mabel giggled,poking LSP.

"OK. Now we just need to get back to the Princess. That potion should be finished by now."

They walked back to the Candy Kingdom and went inside the castle.

"Where were you two? You're lucky I had Finn here to help me or the potion would have taken longer to make."

Bubblegum held up a vial of blue liquid. "I'll just pour it here." She poured it on the ground at her feet.

They looked in and saw the bottom of the tree,where the twins had fallen in.

"Success," PB praised. "Now...if you just jump in this portal you will go back to your world,with no way of getting back here."

"Ok. Come on Mabel."

Mabel picked up as much candy as she could. "OK."

They sat on the edge of the portal.

"Hey. Kid. Take this with you," Jake said, handing Dipper the book.

"Y-you're giving the book back?"

"Yeah. It's your's now."

Dipper smiled. "Well...time to go."

He and Mabel jumped in simultaniously. They landed on the tree's floor.

"Hey...we're back!"

Grunkle Stan peeked in. "Hey! Where were you two at? You were gone for like,ten minutes."

Dipper and Mabel looked up. Nothing but the insides of the tree.

"Oh just out and about."

"Well come on you've got to help me clean up the Shack."

They started to walk. Dipper looked down on the ground and saw an index card. He picked it up. It read:

' So,you found my book and met my sons. Good for you. Now find me to know the truth.'

"Wait,is this-,"

There was rustling in the woods nearby. The three walked back to the Mystery Shack. But Dipper couldn't shake the feeling that,whoever wrote the book, was still here,somewhere.


End file.
